1. Field of the Invention
The present invention relates to a picture signal processing system, a playback apparatus and display apparatus, as well as a picture signal processing method used to display a video signal made up of source data wherein image data, having a total number of pixels greater than the number of visible pixels on a display screen, is moved in a constant direction at a constant speed.
2. Description of the Related Art
For many years, panoramic photographs acquired using film cameras have enjoyed broad popularity. Panoramic photographs can be acquired using special equipment wherein a lens provided in a film camera is mechanically rotated, or by using a film camera provided with a wide-angle lens such that the imaged portion is wide with respect to the film.
Together with decline of film cameras and the broad adoption of digital cameras, taking panoramic photographs using digital cameras has become easier. More specifically, as shown by way of example in FIG. 27, a digital camera may be continuously moved in a rotating manner while successively taking pictures that overlap to some degree along a constant direction (such as vertical or horizontal). Subsequently, stitching or similar software loaded onto a personal computer (PC) is used to join the acquired images in a particular way. As a result, a panoramic image with a field of view much wider than that of the digital camera can be created. For example, Japanese Unexamined Patent Application Publication No. 2007-43505 discloses a method for controlling a camera when taking panoramic images, as well as a method for creating a panoramic image from image data acquired by such control.
Ordinarily, panoramic images created in such a way are often enjoyed as panoramic photographs printed out using a printer or other means. However, enjoying printed panoramic photographs created from digital data is similar to that of panoramic photographs acquired with a film camera in that the experience is static, and lacks the opportunities for enjoyment that digital data enables.
On the other hand, it is conceivable to enjoy created panoramic images by displaying them on the display of a PC. The performance of image sensors such as CCDs (Charge-Coupled Devices) and CMOS (Complementary Metal Oxide Semiconductor) imagers is steadily improving in recent digital cameras, and high-resolution image data can be acquired. For this reason, panoramic images created by joining together such high-resolution image data have high resolutions far exceeding the resolution of the display.
Consequently, when displaying a panoramic image on the display of a PC, the number of pixels in the image data is decreased to match the number of display pixels in the display, for example. However, decreasing the number of pixels in the image data involves operations such as resampling the pixels in the image data, which leads to poorer resolution.
Particularly, panoramic images like those described above typically have high resolutions far exceeding the resolution of the display. For this reason, when displaying panoramic images or similar image data with a very large number of pixels on a display, the image resize ratio becomes extremely large, and the resolution of the image data is lost.
In this way, it is typically difficult to fully enjoy panoramic images on a PC, due to the problem of the screen size and resolution of the display.
It is also conceivable to read and render the image data in integer units of pixels in either the horizontal or vertical direction, using software installed on a PC, for example. In so doing, a panoramic image can be dynamically displayed by being moved at a constant speed, as shown in FIG. 28. More specifically, panoramic image can be enjoyed this way over the Web, using software written in JavaScript™.
However, in this case, the image data might not move smoothly overall, or parts of the image data might be intermittently lost, depending on factors such as the performance of the PC and the operation system (OS). For this reason, it is difficult to stably and cleanly display a panoramic image.
Meanwhile, increased television picture resolution has been realized in recent years, following advances in digital transmission and picture data coding technologies. For example, an interlaced resolution of 1920×1080 pixels (1080i) has been realized for high-definition (HD) video available over current terrestrial digital television broadcasts. Furthermore, a progressive resolution of 1920×1080 pixels (1080p) has also been defined as a standard. In conjunction with the above, television receivers for displaying video on a television have also advanced, and a large number of products having a number of visible display pixels corresponding to HD resolutions are being developed, using technologies such as liquid crystal display (LCD), plasma display panel (PDP), and organic electroluminescence (EL). Furthermore, the High Definition Multimedia Interface (HDMI) has been finalized as an interface standard for transmitting HD television signals. Such television receivers (hereinafter referred to as TVs) have large screen sizes and high resolutions compared to PC displays.
Consider the case wherein a panoramic image is displayed dot-by-dot and dynamically moved across a TV or similar display apparatus that displays pictures at a resolution of 1920×1080 pixels. In this case, the resolution of the panoramic image is converted such that the number of pixels in either the horizontal or the vertical direction of the image matches that of the TV, and then the image is moved at constant speed.
For example, in the case of a wide panoramic image as shown in FIG. 28, the resolution of the image is converted such that the number of pixels in the vertical direction of the image data becomes equal to 1080, the number of pixels in the vertical direction of the display apparatus. Subsequently, the image is moved in the horizontal direction in predetermined pixel units, and synchronously with the refresh rate of the display apparatus. For example, in the case of the NTSC (National Television System Committee) format, the refresh rate of the display apparatus is 60 Hz, and thus the image is moved in the horizontal direction in integer units of pixels (such as 1 or 2 pixels) every 1/60 seconds and synchronously with the refresh rate. In so doing, it becomes possible to play back a panoramic image that moves in pixel units.
In the case of a tall panoramic image, the resolution of the image may be converted such that the number of pixels in the horizontal direction of the image data becomes equal to 1920, the number of pixels in the vertical direction of the display apparatus.
In this case, since the original resolution of the panoramic image is high, the user can view an extremely high-definition panoramic image displayed on a TV, without noticing the imperfections such as noise and Bayer patterns that are characteristic of digital cameras.